Aqueous-Phase Isotope Harvesting to Manufacture Radioactive Targets for

Neutron-Reaction Studies

Scott Essenmacher, Chirag K. Vyas, E. Paige Abel, Katharina Domnanich, Hannah Clause, Colton Kalman, Wes Walker, Gregory Severin

Department of Chemistry, National Superconducting Cyclotron Laboratory,

Michigan State University, East Lansing, Michigan.

Isotope Harvesting has been the topic of a series of workshops sponsored by the DOE since 2010.

INTRODUCTION

INTRODUCTION Opportunities for accessing radionuclides (10-2 yr < T1/2 < 105 yr) from radioactive ion beam facilities.

Process of extracting the selected radionuclides from the beam dump has been coined “Isotope

Harvesting.”

Isotope harvesting as a methodological approach to access radionuclides for applied and basic science

research.

Harvesting can fuel new research using isotopes that will be formed as by products of normal operation

of a rare isotope beam facility such as the Facility for Rare Isotope Beams (FRIB) and its predecessor the

National Superconducting Cyclotron Laboratory (NSCL).

One of the major areas of research that is identified as benefitting from isotope harvesting is

Stewardship Science.

Providing Stewardship Science researchers with radionuclides on the proton and neutron rich sides of

stability with a wholly different impurity spectrum than comes from other isotope production methods,

like light-ion reactions.

• Shusterman et al, Nature 565,328-330 2019.• Isotope harvesting provides access to some of the radiochemical

tracer materials that are needed for stewardship science. • 88Zr measurement has been confirmed with harvested material

(manuscript in preparation).

Radioactive targets

“There are almost no nuclear data for neutron-induced reactions of the radioactive nucleus 88Zr, despite its importance as a diagnostic for nuclear security. Here, by exposing 88Zr to the intense neutron flux of a nuclear reactor, we determine that 88Zr has a thermal neutron capture cross-section of 861,000 ± 69,000 barns”

• There is interest in measuring n,p and n,g reactions on V-48.

• Difficult to obtain a V-48 sample without V-49 contamination.

• Pure V-48 can be obtained from the decay of Cr-48, which we can harvest at NSCL/FRIB.

• At NSCL we could collect ~10^12 48Cr atoms, at FRIB ~10^15

• sensitivity to thermal n,g cross section to ~1 b at NSCL, and ~1 mb at FRIB.

Cr-48 and V-48

The topic of the current proposal is to develop the necessary isotope harvesting techniques for obtaining a pure sample of 48V for neutron reaction studies.

Main reaction pathways for creating 48Cr by heavy-ion irradiation. The fusion of 40Ca and 16O creates the compound 56Ni nucleus, which evaporates nucleons in

a stochastic manner, to populate a spectrum of radioisotopes. The fragmentation, or breakup of 58Ni at higher energy populates a different spectrum of

reaction products.

Production at NSCL/FRIB

Low Power Harvesting Evaluation(1-10 W beam power)M2a) Operation, and measurement of the yields of isotopes

produced by 40Ca and 58Ni irradiation of water.M2b) Production of a 48Cr/48V generator.

High Power Harvesting and Production of Target(50-300 W beam power)M3a) Harvesting, using 40Ca and 58Ni primary beams.M3b) Production of 48V and 49V targets from harvested material.

A Harvesting Dry RunM1a) Upgrade the harvesting systemM1b) Protocol development for isolating and separating chromium

and vanadium.

YEAR - I

YEAR - II

YEAR - III

PROJECT MILESTONES

ChemE MILESTONES FOR YEAR-I Year 1: A harvesting dry runM1a) Development of a harvesting system for online collection of isotopes from water that is irradiated witha primary heavy-ion beam.

S1. A: Upgrade the harvesting system

Demonstrable Goals:1. A completely fabricated “harvesting system” including

a. Titanium target body installed (already designed and fabricated using start-up funding)

b. A cooling loop capable of moving water through the target at 6 gpm (4.5 gpm) at an operating pressure ofless than 5 barg, and capable of retaining a water temperature of less than 30 ℃ with a 500W heat load,with pressure, temperature, and flow-rate monitoring.

c. A purification loop operating at least 0.2 gpm (700 mL/min or 0.2 gpm), moving water through analyticsincluding pH, conductivity, temperature and dissolved oxygen before and after resin beds

d. A gas-phase vent line for evolved gases (especially H2) with sorbing traps for gas phase radioactivity (e.g.soda lime for [11C]CO2) and cold-traps for noble gas trapping.

HARVESTING SYSTEM

Installed Harvesting System

at NSCL

HARVESTING SYSTEMBeam Blocker

HARVESTING SYSTEMCT Scan of a Beam Blocker

HARVESTING SYSTEM

ChemE MILESTONES FOR YEAR-I Year 1: A harvesting dry runM1a) Development of a harvesting system for online collection of isotopes from water that is irradiated witha primary heavy-ion beam.

S1. A: Upgrade the harvesting system

Demonstrable Goals:1. A completely fabricated “harvesting system” including

a. Titanium target body installed (already designed and fabricated using start-up funding)

b. A cooling loop capable of moving water through the target at 6 gpm (4.5 gpm) at an operating pressure ofless than 5 barg, and capable of retaining a water temperature of less than 30 ℃ with a 500W heat load,with pressure, temperature, and flow-rate monitoring.

c. A purification loop operating at least 0.2 gpm (700 mL/min or 0.2 gpm), moving water through analyticsincluding pH, conductivity, temperature and dissolved oxygen before and after resin beds

d. A gas-phase vent line for evolved gases (especially H2) with sorbing traps for gas phase radioactivity (e.g.soda lime for [11C]CO2) and cold-traps for noble gas trapping.

Chemistry MILESTONES FOR YEAR-I Year 1: Development of Harvesting ChemistryM1b) Development of a protocol for isolating and separating trace levels of chromium and vanadium from neutralizedirradiated water.

S1. B: Development of the Cr and V-specific harvesting chemistry

Demonstrable goals:

1. Determination of Kd values for chromate, vandanyl and vanadate on AG1x8 from pure water, and fromwater with varying concentrations of H2O22. A column-based method for extracting Cr(VI) and V(V) from neutral water with low levels of H2O2.

3. A column-based method for separation of extracted V(V) from Cr(VI) from AG1x8

V and Cr CHEMISTRY

1Pourbaix diagram (A) vanadium (B) chromium in aqueous solutions (conc. of 10-10 mol/kg)

• 𝐸𝐸𝑆𝑆𝑆𝑆𝑆𝑆0 = 1.776 𝑉𝑉 for H2O2• Bottom line is calculated electrode potential for the solution with 1 ppb O2 less about 100 mV • O2 concentration increases with exposure to beam

A B

2Dissolved O2 in solution for experiment involving the target being irradiated with

140 MeV/u 48Ca20+ ions

1Takeno, N. Atlas of Eh-pH Diagrams. Intercomparison of thermodynamic databases; 419; Geological Survey of Japan: 2005.2Domnanich K. et al., Nuclear Inst. and Methods in Physics Research A; 2020.

Nuclide Cation Resin Anion Resin Degrader Water Total

48V - 0.54(3) kBq - - 0.54(3) kBq

48Cr - 0.79(6) kBq - - 0.79(6) kBq

48V and 48Cr were found to be collected on AG1-X8 anion exchange resin in prior experiments involving the irradiation of the target with 140 MeV/u 40Ca20+ ions.

48V and 48Cr Accumulation in the System

Abel, E.P., Clause, H., and Severin, G.W., Applied Radiation and Isotopes; 2020.

V and Cr CHEMISTRY

Distribution Coefficients with AG1-X8 Anion Exchange Resin

*Experimental Parameters *n = 3; Aqueous Phase Volumes = 20 mL; Average Resin Weight = ~132 mg

Equilibration time = 24 hr; Temperature = 25 °CLDL for V and Cr by ICP-OES= 100 ppb

Metal Ion Conc. (ppm)

V (5+ as VOCl3) Cr (6+ as CrO2Cl2)

pH 5 pH7 pH 3-4.5 pH 5 pH7 pH 3-4.7

1 > 3E+05 >3E+05 > 3E+05 > 3E+05 > 3E+05 >3E+05

10 >3E+05 >3E+05 >3E+05 > 3E+05 >3E+05 >3E+05

20 >3E+05 2.07E+05 >3E+05 >3E+05 >3E+05 >3E+05

V and Cr CHEMISTRY

Distribution Coefficients with AG1-X8 Anion Exchange Resin in the Presence of H2O2

*Experimental Parameters *n = 3; Metal Ion Concentration = 20 ppm; Aqueous Phase Volumes = 20 mL;

Average Resin Weight = ~132 mgEquilibration time = 24 hr; Temperature = 25 °C

LDL for V and Cr by ICP-OES= 100 ppb

H2O2 Conc. (µM)V Cr

pH 3-4.5 pH 3-4.7

100 > 3E+05 2.10E+05

500 >3E+05 1.51E+04

1000 2.09E+05 5.67E+03

V and Cr CHEMISTRY

Loading studies of V and Cr with AG1-X8 Anion Exchange Resin (1.5g) Columns

Loading of 1 ppm V and Cr at 300 mL/min for 24h(actual speed of water flow in system)

V and Cr CHEMISTRY

GeGI Dynamic Pinhole Imaging Measurements: 51Cr in Greg

Severin’s Laboratory

August 9, 2018

GeGI Dynamic Pinhole Imaging Measurements: 51Cr in Greg Severin’s Laboratory

August 9, 2018

Overview

Demonstration data collected in the chemistry laboratory of Greg Severin at Michigan State University

Mock 51Cr separation was set up and monitored with GeGI in Pinhole Imaging mode (5-mm pinhole aperture)

Images were analyzed using Imager32 onboard quantification algorithms

Uncertainties are dominated by the error in the distance measurement, assumed to be +/- 2 cm;

No attempt was made to account for attenuation of the 51Cr gamma rays by the water in the reservoir or material in the column (though this can be done in the software);

This is likely the cause of the difference between the calculated initial activity in the reservoir and final activity in the column.

51Cr Activity vs. Time

Animation of 51Cr Distribution

Each image represents a 5-minute data acquisition

Cr-51 Measurements in the lab of Greg Severin at MSU5-minutes acquisition periods

8/9/18

Time Index Value Uncertainty Value Uncertainty0 259 20 0 01 173 17 127 142 93 10 260 273 43 6 330 344 18 4 346 355 12 3 351 356 7 3 359 367 0 0 375 398 0 0 360 369 0 0 362 36

10 0 0 378 3811 0 0 386 3912 0 0 370 3713 0 0 355 3514 0 0 345 35

Reservoir Activity (uCi) Column Activity (uCi)

-50

0

50

100

150

200

250

300

350

400

450

0 2 4 6 8 10 12 14 16

Activ

ity (u

Ci)

Time (5-minute intervals)

Cr-51 Activity vs. Time

Reservoir Column

Cr-51 Measurements in the lab of Greg Severin at MSU

5-minutes acquisition periods

8/9/18

Time IndexValueUncertaintyValueUncertainty

025920 00

117317 12714

29310 26027

3436 33034

4184 34635

5123 35135

673 35936

700 37539

800 36036

900 36236

1000 37838

1100 38639

1200 37037

1300 35535

1400 34535

Reservoir Activity (uCi)Column Activity (uCi)

-50

0

50

100

150

200

250

300

350

400

450

0246810121416

A

c

t

i

v

i

t

y

(

u

C

i

)

Time (5-minute intervals)

Cr-51 Activity vs. Time

ReservoirColumn

Elution studies of V and Cr with AG1-X8 Anion Exchange Resin (1.5g) Columns

Recovery Yield: V = 85.8 %; Cr = 57.7 %

V and Cr CHEMISTRY

Chemistry MILESTONES FOR YEAR-I Year 1: Development of Harvesting ChemistryM1b) Development of a protocol for isolating and separating trace levels of chromium and vanadium from neutralizedirradiated water.

S1. B: Development of the Cr and V-specific harvesting chemistry

Demonstrable goals:

1. Determination of Kd values for chromate, vandanyl and vanadate on AG1x8 from pure water, and fromwater with varying concentrations of H2O22. A column-based method for extracting Cr(VI) and V(V) from neutral water with low levels of H2O2.

3. A column-based method for separation of extracted V(V) from Cr(VI) from AG1x8

Upcoming Campaigns Kd evaluation for V and Cr with AG1-X8 anion exchange resin with varying concentrations

high acidity solutions of HCl/ HNO3 to predict the elution and separation behavior from thecolumn.

Determination of plausible metal ion species eluted with Cr and develop protocol for itspurification.

Develop protocol for 48Cr/48V generator.

Acknowledgements

This material is based upon work supported by the U.S. Department of Energy,National Nuclear Security Administration.

Disclaimer: This report was prepared as an account of work sponsored by an agency of the UnitedStates Government. Neither the United States Government nor any agency thereof, nor any of theiremployees, makes any warranty, express or implied, or assumes any legal liability or responsibilityfor the accuracy, completeness, or usefulness of any information, apparatus, product, or processdisclosed, or represents that its use would not infringe privately owned rights. Reference herein toany specific commercial product, process, or service by trade name, trademark, manufacturer, orotherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring bythe United States Government or any agency thereof. The views and opinions of authors expressedherein do not necessarily state or reflect those of the United States Government or any agency

Slide Number 1Slide Number 2Slide Number 3Radioactive targetsCr-48 and V-48Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24